Soon after its world premiere last year, 12 Years a Slave was widely described as the best film that has yet been made about American slavery.

That’s a big claim — and, I believe, an accurate one — although it raises an interesting question. Where, exactly, is the competition?

The new filmfrom the British director Steve McQueen is an adaptation of the memoirs of Solomon Northup, a freeborn black American family man from upstate New York who was kidnapped, shipped to the South and sold to the owner of a Louisiana plantation in 1841. There have been other films about American slaves, and films that have described or depicted the American slave trade in some way too: not many, but enough high-profile ones, from Gone With the Wind all the way to Mandingo, for the topic not to feel like unmapped territory.

But films that are actually about American slavery are vanishingly rare — films that unpick slavery’s all-debasing power-plays, enumerate its everyday horrors, show us the rhythms and rituals that have left it lingering in that nation’s muscle memory. McQueen’s picture, nominated for 10 Baftas this week withOscars sure to follow, does all of this, and could be the first of a new genre.

Chiwetel Ejiofor in 12 Years a SlaveCredit:
Rex

Solomon is played by Chiwetel Ejiofor: an enormously talented English actor getting the right break at the ideal moment. In the film’s early scenes, we watch Solomon stroll around his home town of Saratoga with his wife (Kelsey Scott) and children, and, Ejiofor moves with a gentle confidence that makes his later imprisonment seem not just inhuman, but illogical.

Then, when we first see him in chains, hemmed in by shadows in a dingy cell and lit by a thick strip of moonlight, we are shocked for the same reason he is: we see a free man with his movement wrongly restricted. Then his captor comes in, taunts him, calls him nigger and beats him with a wooden paddle until it splits in two.

Of course the language and violence in 12 Years a Slave makes you wince, but the brutality here is as sleek as a knitting needle, and slips between your ribs to get at you somewhere deep, beyond simple expressions of disgust or disbelief. McQueen has no intention of turning his film into a Western liberal guilt-trip — he doesn’t have to. What we see speaks for itself. The entire nation, south and north alike, is in the grip of communal insanity.

Solomon is taken by boat to New Orleans, where Paul Giamatti’s diabolic trader gives him his slave name, Platt, and sells him to Benedict Cumberbatch’s anxious plantation owner, Ford, as part of a package deal.

Under Ford’s ownership, Solomon makes the best of his apocalyptically bad lot, but he runs into trouble with an overseer played by Paul Dano — so weaselly here, you can picture him emerging from a chicken coop with a bird between his teeth. A lynching is attempted, and fails, but only just. We watch Solomon hanging from the branch of a cypress tree, his tiptoes slip-slip-slipping in the mud underfoot, his throat stretched long by the noose, his breath coming in shallow clucks. Behind him, the other slaves meekly go about their business, but McQueen doesn’t let us join them. He holds the shot, and then holds it for longer.

That unflinching gaze is McQueen’s signature move, as viewers of his first two features, the Bobby Sands biopic Hunger and the sex-addiction drama Shame, will already know. Later, when Solomon is on another plantation presided over by the maniacal Epps (Michael Fassbender), McQueen stages an even longer single-shot scene in which the master flogs a field girl, Patsey (Lupita Nyong’o, making her film debut) with whom he is obsessed. He hands the whip to Solomon, making him complicit in the torture. It’s madness. It has to be. But it’s also true, and these three astonishing performances, and that unblinking camera, convince you of it.

A year ago almost to the day, I wrote in the Telegraph about Quentin Tarantino’s Django Unchained: another film centred on a slave’s survival in the antebellum South. I loved Tarantino’s picture, but the two films can’t be sensibly compared. Django’s most startling scenes come glazed with irony, and it ends with a cathartic bloodbath that allows us to leave the cinema feeling that justice, of a limited sort, has been served. McQueen is working with no such protection.

To measure the importance of this we must go back to 1915. That year saw the release of D.W. Griffiths’ The Birth of a Nation: the historical epic, set during the American Civil War and its aftermath, that inscribed the rules that govern to this day how films are built, watched and loved. It was a smash hit. Its importance cannot be overstated. It was the first film to be screened in the White House, and Woodrow Wilson, the then-President, called it “history written with lightning”.

But Griffiths’ film has almost no truth in it — and it is monstrously, numbingly racist. Its black characters are drunks and rapists, played by gurning white actors in blackface, while the Ku Klux Klan are shown to be saviour knights of the new republic. Think again of that strange lack of films about American slavery, and wonder how long it will take for cinema to exorcise these demons. In that light, 12 Years a Slave isn’t simply a masterpiece, it’s a milestone. This, at last, really is history written with lightning.